In piping and facilities in factory plants and buildings, multiple instruments such as pressure gauges and thermometers, are used. These instruments are inspected and managed daily for checking operation states of the facilities and devices, and managing safety. In the daily inspection, for example, common reference measurement values for the facilities are checked and whether or not an indication is abnormal is checked. Further, for important portions such as pressure vessels for boilers, not only a periodic legal inspection is performed, but also a user periodically requests each instrument manufacturer to perform calibration of the instrument, in general.
At this time, for the management of the instruments, in general, a seal on which a management number, such as an instrument tag number, of each instrument is defined and indicated, is attached to an transparent plate or a scale plate on the front face of the instrument, or an exterior portion of the instrument, and the instruments are individually managed, in many cases. Further, as such management of the instruments, management using bar codes is performed in some cases. However, in recent years, since RFID tags are available at relatively low prices, it is desired that the RFID tags into which data can be written and from which data can be read be used in this field.
As a technique for automating management of the instruments and managing calibration time limits with enhanced accuracy, for example, the techniques disclosed in Patent Documents 1 to 3 are suggested. According to these techniques, a maintenance support system can be provided which can support, by using an instrument having an RFID mounted thereto, various operations associated with inspection and maintenance, of facilities and devices, which require time and cost and, further, are difficult for persons other than experienced persons, such that the operations associated therewith can be efficiently performed with high quality.
However, in the techniques disclosed in these patent documents, an RFID tag that has been incorporated into the instrument is used, and the techniques are effective for a system into which an instrument is newly introduced. Meanwhile, the structures of the techniques are not proper for supporting maintenance of instruments which have been already installed. In general, in the instrument and the like, a material of the exterior case is a metal in many cases, and further a piping connection portion is made of a metal. Therefore, since a typical RFID tag is influenced by the metal when the RFID tag is read, consideration is required for the mounting such that, for example, a metal-compatible tag is used for the exterior portion of the instrument. Further, the scale plate is typically made of a metal in general. Therefore, consideration is required so as to use a metal-compatible tag. However, a metal-compatible tag is not proper for attachment to the scale plate due to a problem associated with space or the like.
Further, as an instrument having an improved vibration resistance and durability, a glycerin-enclosing type product in which a mechanism inside a casing is completely soaked in aqueous solution of glycerin, and influence of vigorous vibration on the internal mechanism and influence of an amplitude thereon are inhibited, and abrasion is reduced due to viscosity resistance of glycerin, to improve durability, is often found. However, for any of these products, a casing made of a metal is used, and the inside of the instrument is immersed in glycerin, and it is thus difficult to use the RFID tag on both the outer side and the inner side of the instrument.